// Bit reversal implementation using masks.
// http://aggregate.org/MAGIC/#Bit%20Reversal

unsigned reverse(unsigned x) // Assuming 32 bit integers
{
    x = ((x & 0xaaaaaaaa) >> 1) | ((x & 0x55555555) << 1);
    x = ((x & 0xcccccccc) >> 2) | ((x & 0x33333333) << 2);
    x = ((x & 0xf0f0f0f0) >> 4) | ((x & 0x0f0f0f0f) << 4);
    x = ((x & 0xff00ff00) >> 8) | ((x & 0x00ff00ff) << 8);
    return (x >> 16) | (x << 16);
}
